The present invention relates to a horizontal mold clamping and vertical injection type die casting method and apparatus, wherein a molten metal is casted into a cavity of a metal mold, clamped in the horizontal direction, from the lower direction.
Die casting methods and apparatuses therefor are classified into those of a horizontal mold clamping type and those of a vertical mold clamping type according to the mold clamping direction, and are also classified into those of a vertical injection type and those of a horizontal injection type according to the molten metal injection direction. Among them, the horizontal mold clamping and vertical injection type die casting method and an apparatus therefor are developed by the present applicant and disclosed in U.S. Pat. Nos. 4,655,274 and 4,690,197. This method and the apparatus therefor are widely practically used since they have many excellent points, e.g., a temperature decrease in molten metal due to a contact with a casting sleeve is low, gas entrainment of the molten metal in the sleeve is small, and degassing of the cavity can be performed well, thus providing good cast products.
FIG. 1 is a partially sectional side view of a die cast machine for explaining the conventional die casting method of this type. The conventional die casting method will be described with reference to FIG. 1. A stationary platen 2 and a link housing 3 are fixed by tie rods 4 at four corners thereof and oppose each other on a machine base 1. A movable platen 5 is supported by the tie rods 4 such that it is horizontally movable with respect to the stationary platen 2. A stationary metal mold 6 is mounted on the stationary platen 2 and a movable metal mold 7 is mounted on the movable platen 5. The metal molds 6 and 7 oppose each other. A cavity 8 as a hollow portion is formed in the split or mating plane of the mated metal molds 6 and 7, as shown in FIG. 1. A mold clamping cylinder 9 is fixed to the central portion of the housing 3. The operating end of a piston rod 10 of the cylinder 9 is connected to a part of a toggle mechanism 11 provided between the movable platen 5 and the link housing 3. When the mold clamping cylinder 9 is operated, the movable platen 5 is moved forward/backward to mate or clamp/open the metal molds 6 and 7. A plurality of brackets 12 are fixed to the movable metal mold 7, and core cylinders 13 are mounted to the respective brackets 12. A slide core 15 is provided to the piston rod of each core cylinder 13. When the piston rods of the core cylinders 13 are moved forward/backward, the slide cores 15 are engaged/disengaged with/from the undercut portion of the cavity 8.
An injection cylinder unit 17 is pivotally supported by a support frame 16 extending downward from the lower end of the stationary platen 2 and can stand upright or be tilted. A block 20 is bonded to the upper end of an injection cylinder 18 as a main portion of the injection cylinder unit 17 and is vertically moved by a cylinder 19. A casting sleeve 21 is supported by the block 20 and inserted in a sleeve hole defined by the metal molds 6 and 7. When the cylinder 19 is operated, the casting sleeve 21 is vertically moved together with the block 20 and engaged with or disengaged from the metal molds 6 and 7. A tilting cylinder 22 is supported by the support frame 16 through a bracket 23. When the casting sleeve 21 is disengaged form the metal molds 6 and 7, the tilting cylinder 22 tilts the entire portion of the injection cylinder unit 17 to supply molten metal into the casting sleeve 21. A plunger tip (not shown) for moving forward/backward within the casting sleeve 21 is coupled to the piston rod of the injection cylinder 18. When the plunger tip is moved upward, the molten metal is injected into the cavity 8.
A push out cylinder 24 of a product push out device is mounted to the central portion of the counter-metal mold side of the movable platen 5. A push out plate 25 is fixed to the piston rod of the push out cylinder 24. A plurality of connecting rods 26, each having an end fixed to the push out plate 25, extend through the movable platen 5 and project into the hollow portion of the movable metal mold 7. A push out plate 27 is mounted to the projecting ends of the connecting rods 26. A plurality of push out pins 28, each having an end held by the push out plate 27, extend through the movable metal mold 7 and project to the interior of the cavity 8. When the molds are opened, the push out pins 28 are moved forward by the push out cylinder 24 and push the product out of the cavity 8. A manifold 29 having a valve is fixed to the movable platen 5 and distributes pressurized oil to the core and push out cylinders 13 and 24.
With the above arrangement, the molds 6 and 7 are clamped as shown in FIG. 1, the injection cylinder 18 is tilted to supply the molten metal into the casting cylinder 21, and the injection cylinder 18 is caused to stand upright. The casting sleeve 21 is inserted into the sleeve hole defined by the metal molds 6 and 7, and the plunger tip of the piston rod in the injection cylinder 18 is moved forward to cast the molten metal into the cavity 8. After the molten metal in the cavity 8 is solidified and cooled, the mold clamping cylinder 9 is operated. Then, the movable platen 5 is moved backward through the toggle mechanism 11 and the movable metal mold 7 is moved backward to open the molds 6 and 7. In this case, the slide core 15 is closed and the product is held by the movable metal mold 7. Thus, the molds 6 and 7 are opened while the product is attached to the movable metal mold 7. When mold opening is completed, the core cylinder is operated to move the slide core 15 upward to disengage it from the product. Then, the push out cylinder 24 is operated so that the push out plate 25, the connecting rod 26, the push out plate 27, and the push out pin 28 are integrally moved forward and the product is pushed. The pushed product is picked up by a product pickup device (not shown) from the casting machine.
However, in the conventional horizontal mold clamping and vertical injection type die casting machine described above, a product push out operation can be started only after the molds are completely opened and the slide core 15 is opened since otherwise the product can undesirably fall. Since a time required for product push out in a single die casting cycle time is considerably increased, the entire cycle time cannot be shortened, thus resulting in high manufacturing cost. Regarding the mold opening operation, not only the movable platen 5 and the movable metal mold 7 are moved, but also heavy components such as the product push out device, the core cylinder 13, and the manifold 29, as well as the product, must be moved. It takes time for these components to reach the maximum speed, overcoming static friction, from the still state. As a result, the time required for product push out is further elongated, and the power consumption is increased.